(1) Field of the Invention
The present invention relates to a process for the preparation of a 2N, 6N-diamino-amino acid-xcex2-hydroxy disuccinic acid, as a N,N-diacid salt, in particular 2N, 6N-dilysine-xcex2-hydroxy disuccinic acid as a N,N-dihydrochloride salt. Any of the compounds can be converted to an alkali metal salt from (Na, K). The process involves reaction of a diamino acid as an acid salt with epoxy succinic acid. The amino acids can be in D or L isomers and the epoxy succinic acid can be in a cis- or trans- form.
(2) Description of Related Art
Japanese Patent No. 8067659A describes a basic reaction of lysine or its potassium or ammonium salts and an epoxy amino acid or its salts under neutral or basic conditions to produce lysine disuccinic acid compounds which are useful as chelators. The lysine is as the free amine. The process requires acidulation of the reaction mixture to form an acid salt which is separated as an additional step.
The preparation of epoxy succinic acid is described in U.S. Pat. No. 5,905,160 to Shimomura et al. An ethylamine compound is epoxidated with hydrogen peroxide.
There is a need for an improved process for the preparation of the disuccinic acid derivatives.
It is therefore an object of the present invention to provide an improved process for the preparation of the succinic acid derivatives. It is further an object of the present invention to provide a process which is relatively easy to perform and which is economical.
The present invention relates to a process for the preparation of a N,N-diamino-amino acid-xcex2-hydroxy disuccinic acid (I) as a N,N diacid salt which comprises: reacting an N-acid salt of an N,N-diamino-amino acid with epoxy succinic acid in a solvent; and separating (I) from the reaction mixture. The preferred amino acid is lysine. The process is preferably conducted in an aqueous solution as the solvent heated to less than 100xc2x0 C., in the absence or presence of oxygen. The reaction is most preferably conducted under a nitrogen atmosphere. The separation is preferably conducted by adding ethanol and/or the methanol to the solution which is removed with the aqueous solution, and wherein I is washed with ethanol and solvent to purified I.
The process produces a N,N-diamino-amino acid-xcex2-hydroxy disuccinic acid as an N,N-diacid salt and in particular 2N,6N-lysine-xcex2-hydroxy disuccinic acid as a N,N-dihydrochloride salt. The preferred compound has the formula (II) 
The acids used can be any mineral or organic acid which forms a salt with the amino acid. Most commonly an inorganic acid such as hydrochloric acid is used for cost reasons, although sulfuric acid can be used.
The amino acids can be asparagine, glutamine, tryptophan, argenine, histidine and lysine, which are preferred for reasons of cost.